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<head><meta charset="utf-8"><title>Min Supported LLVM Upgrade Process? · t-compiler/help · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/index.html">t-compiler/help</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Min.20Supported.20LLVM.20Upgrade.20Process.3F.html">Min Supported LLVM Upgrade Process?</a></h3>

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<a name="215948968"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/Min%20Supported%20LLVM%20Upgrade%20Process%3F/near/215948968" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> DevJPM <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Min.20Supported.20LLVM.20Upgrade.20Process.3F.html#215948968">(Nov 07 2020 at 10:39)</a>:</h4>
<p>While working on <a href="https://github.com/rust-lang/rust/pull/78361">https://github.com/rust-lang/rust/pull/78361</a> I noticed that the minimum supported version of LLVM for building Rust is 8.<br>
For this specific PR this actually forced me to cut down and defer enabling specific codegen features (x86 CPU Extensions) because they were only introduced in LLVM 9. <br>
Because of this I'd like to have some way of knowing when the minimum supported LLVM version is bumped to &gt;=9 so I can PR the change that is already prepared but is now commented out.</p>
<p>So, is there some document somewhere (that I failed to find) that describes when the minimal supported LLVM version is bumped?<br>
(or alternatively some sort of tracking issue for the current minimal LLVM version)</p>
<p>(The only thing I could find is a discussion for a bump to LLVM 6 from 2018 <a href="https://github.com/rust-lang/rust/issues/55842">https://github.com/rust-lang/rust/issues/55842</a>)</p>



<a name="215957669"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/Min%20Supported%20LLVM%20Upgrade%20Process%3F/near/215957669" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Joshua Nelson <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Min.20Supported.20LLVM.20Upgrade.20Process.3F.html#215957669">(Nov 07 2020 at 14:37)</a>:</h4>
<p><span class="user-mention" data-user-id="138448">@cuviper</span> might know</p>



<a name="215957859"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/Min%20Supported%20LLVM%20Upgrade%20Process%3F/near/215957859" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> cuviper <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Min.20Supported.20LLVM.20Upgrade.20Process.3F.html#215957859">(Nov 07 2020 at 14:41)</a>:</h4>
<p>I don't think we've written any real policy on this, but I think bumping to 9 would be ok now</p>



<a name="215969611"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/Min%20Supported%20LLVM%20Upgrade%20Process%3F/near/215969611" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> DevJPM <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Min.20Supported.20LLVM.20Upgrade.20Process.3F.html#215969611">(Nov 07 2020 at 19:31)</a>:</h4>
<p>Is there a way to (formally) request this short of making a PR with the bump myself (and hoping to find all the places where LLVM 8 might still be used)?</p>



<a name="215969738"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/Min%20Supported%20LLVM%20Upgrade%20Process%3F/near/215969738" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> DevJPM <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Min.20Supported.20LLVM.20Upgrade.20Process.3F.html#215969738">(Nov 07 2020 at 19:34)</a>:</h4>
<p>Speaking of hoping, a search for <code>llvm path:/.github</code> and <code>llvm path:/src/ci</code> revealed the following files which are still on LLVM 8 (though I think both Windows and Apple are already on &gt;=10):</p>
<ul>
<li><a href="https://github.com/rust-lang/rust/blob/b2d115f6db5172c961dfeb50de15f35784dbc7c9/src/ci/docker/host-x86_64/x86_64-gnu-llvm-8/Dockerfile">https://github.com/rust-lang/rust/blob/b2d115f6db5172c961dfeb50de15f35784dbc7c9/src/ci/docker/host-x86_64/x86_64-gnu-llvm-8/Dockerfile</a></li>
<li><a href="https://github.com/rust-lang/rust/blob/b2d115f6db5172c961dfeb50de15f35784dbc7c9/src/ci/docker/host-x86_64/x86_64-gnu-llvm-8/Dockerfile">https://github.com/rust-lang/rust/blob/b2d115f6db5172c961dfeb50de15f35784dbc7c9/src/ci/docker/host-x86_64/x86_64-gnu-llvm-8/Dockerfile</a></li>
<li><a href="https://github.com/rust-lang/rust/blob/b2d115f6db5172c961dfeb50de15f35784dbc7c9/src/ci/github-actions/ci.yml">https://github.com/rust-lang/rust/blob/b2d115f6db5172c961dfeb50de15f35784dbc7c9/src/ci/github-actions/ci.yml</a></li>
<li>(indirectly) <a href="https://github.com/rust-lang/rust/blob/b2d115f6db5172c961dfeb50de15f35784dbc7c9/.github/workflows/ci.yml">https://github.com/rust-lang/rust/blob/b2d115f6db5172c961dfeb50de15f35784dbc7c9/.github/workflows/ci.yml</a></li>
</ul>
<p>is there something missing here?</p>



<a name="215969827"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/Min%20Supported%20LLVM%20Upgrade%20Process%3F/near/215969827" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Min.20Supported.20LLVM.20Upgrade.20Process.3F.html#215969827">(Nov 07 2020 at 19:37)</a>:</h4>
<p>Almost all Rust builders use our own fork of LLVM (currently at 11 with some patches atop that). The llvm-8 builder attempts to verify that we still support an older version of LLVM; we can likely bump that to LLVM 9 in a PR</p>



<a name="215969832"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/Min%20Supported%20LLVM%20Upgrade%20Process%3F/near/215969832" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Min.20Supported.20LLVM.20Upgrade.20Process.3F.html#215969832">(Nov 07 2020 at 19:37)</a>:</h4>
<p>I don't think there's any "request" necessary here, I would just put up a PR doing so.</p>



<a name="215971078"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/182449-t-compiler/help/topic/Min%20Supported%20LLVM%20Upgrade%20Process%3F/near/215971078" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> DevJPM <a href="https://rust-lang.github.io/zulip_archive/stream/182449-t-compiler/help/topic/Min.20Supported.20LLVM.20Upgrade.20Process.3F.html#215971078">(Nov 07 2020 at 20:07)</a>:</h4>
<p>Ok, I've put a PR up, it's here: <a href="https://github.com/rust-lang/rust/pull/78848">https://github.com/rust-lang/rust/pull/78848</a> and also notifying <span class="user-mention" data-user-id="119009">@eddyb</span>  here because of the hack which can be removed now (?) which is mentioned in the PR</p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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